Process for production of expanded thermoplastic elastomer

Patent metadata

Field	Value
Publication number	US-11142625-B2
Application number	US-201415029686-A
Country	US
Kind code	B2
Filing date	Oct 17, 2014
Priority date	Oct 18, 2013
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

The invention relates to a process for production of expanded thermoplastic elastomer, said process comprising the steps of:(e) adding monomers and/or oligomers used for producing the thermoplastic elastomer with or without further starting materials into a first stage of a polymer-processing machine,(f) mixing the monomers and/or oligomers and also the optionally added further starting materials and reacting the monomers and/or oligomers to give a polymer melt in the first stage of the polymer-processing machine,(g) passing the polymer melt into a second stage of a polymer-processing machine and adding a physical blowing agent with or without further starting materials to obtain a polymer melt comprising a blowing agent,(h) molding the polymer melt comprising a blowing agent into an expanded thermoplastic elastomer.

First claim

We claim:

1. A process for production of pellets of expanded thermoplastic polyurethane, the pellets having a bulk density in a range from 80 g/l to 140 g/l, said process comprising the steps of:
(a) adding monomers and/or oligomers used for producing the thermoplastic elastomer with or without further starting materials into a first stage of a polymer-processing machine,
(b) mixing the monomers and/or oligomers and also the optionally added further starting materials and reacting the monomers and/or oligomers to give a polymer melt in the first stage of the polymer-processing machine,
(c) immediately or directly passing the polymer melt into a second stage of the polymer-processing machine and adding a physical blowing agent with or without further starting materials to obtain a polymer melt comprising a blowing agent, wherein the blowing agent comprises 50 wt % to 100 wt % carbon dioxide and 0 wt % to 50 wt % nitrogen and no further blowing agent,
(d) molding the polymer melt comprising a blowing agent into pellets of expanded thermoplastic polyurethane in a system for producing a pellet material which follows the second stage wherein the first stage of the polymer-processing machine and the second stage of the polymer-processing machine are parts of one machine.

2. The process according to claim 1 , wherein the polymer-processing machine is a screw-plunger machine.

3. The process according to claim 2 , wherein the first stage of the screw-plunger machine and the second stage of the screw-plunger machine are sectors of an extruder.

4. The process according to claim 2 , wherein the first stage of the screw-plunger machine is a first extruder of a tandem extruder and the second stage of the screw-plunger machine is a second extruder of the tandem extruder.

5. The process according to claim 2 , wherein the second stage of the polymer-processing machine comprises a melt pump, optionally with a melt sieve or a static mixer.

6. The process according to claim 1 , wherein the pellet material is obtained by forcing the polymer melt in step (d) through a pelletizing die regulated to a temperature in the range from 150 to 280° C., using a cutting device to cut the polymer melt forced through the temperature-regulated pelletizing die into individual expanding pellets and using a stream of liquid to export the pellets from the pelletizing chamber.

7. The process according to claim 6 , wherein a temperature-regulated liquid flowing through the pelletizing chamber as a stream has a temperature in the range from 10 to 60° C. and a pressure in the range from 0.7 to 20 bar above ambient pressure.

8. The process according to claim 1 , wherein the expanded pellet material has a bead weight in the range from 1 to 40 mg.

9. The process according to claim 1 , wherein the expanded thermoplastic elastomer has an uninterrupted skin.

10. The process according to claim 1 , wherein upon the completion of step (c) then step (d) is directly performed.

Assignees

• Basf Se

Inventors

• Gutmann Peter
• Däschlein Christian
• Ahlers Jürgen
• Marten Elke
• Kaminsky Torben
• Kempfert Dirk

Classifications

• C08J9/144

  containing carbon, halogen and hydrogen only · CPC title

• C08J9/127

  Mixtures of organic and inorganic blowing agents · CPC title

• B29C44/3461

  Making or treating expandable particles · CPC title

• B29B7/88

  Adding charges {, i.e. additives} · CPC title

• C08J9/16

  Making expandable particles · CPC title